Manually integrating G2A Payment Gateway

I'm creating a new website which we will be exchanging virtual gold from the called Runescape. I have already created the website, the design and everything. You can check it out link is down below. After a long process we have been verified by G2A too. Now i need to integrate their payment gateway but sadly wix is not a supported CMS platform so it doesn't have a plugin. It must be done manually. I'm looking for a developer who is willing to do this job. Here is the website: [login to view URL]